Multiple-port bidirectional converter and control method thereof

Abstract

A bidirectional DC-DC converter with three or more ports is described along with a method of operation thereof. The converter utilizes a common transformer for all ports and allows for power transfer from any port to any or all of the remaining ports. The converter may utilize a controller which implements variable-frequency control, delay-time control, and/or phase-delay control to achieve power transfer as desired between the converter ports. In some cases, power transfer between ports can operate similar to a series-resonant converter or a dual active bridge converter.

What is claimed is: 
     
       1. A multiple-port converter, comprising:
 a transformer having a primary winding, a secondary winding and a tertiary winding; 
 a primary power stage having a first plurality of switches and electrically connected to a first energy source and the primary winding of the transformer; 
 a secondary power stage having a second plurality of switches and at least a resonant capacitor and a resonant inductor connected in series, and electrically connected to a second energy source and the secondary winding of the transformer, the primary power stage and secondary power stage forming a series resonant converter with an associated resonance frequency determined by the resonant capacitor and the resonant inductor; 
 a tertiary power stage having a third plurality of switches and at least an inductor and electrically connected to a third energy source and the tertiary winding of the transformer, the primary power stage and tertiary power stage forming a dual active bridge converter with an associated inductance between the primary power stage and the tertiary power stage; and 
 a controller electrically connected to the primary, secondary, and tertiary power stages to measure operating conditions in the multiple-port converter and to provide control signals to the first, second and third plurality of switches; 
 wherein the controller comprises control logic configured to send the control signals to the first, second, and third plurality of switches, the control logic of the controller is configured to vary a switching frequency of the first plurality of switches or the second plurality of switches to regulate current corresponding to the second energy source, 
 wherein the secondary power stage and the tertiary power stage are controlled independently from each other. 
 
     
     
       2. The multiple-port converter of  claim 1 , wherein the controller comprises control logic configured to send the control signals to the first and second plurality of switches to transfer energy between the first energy source and the second energy source using phase delay control. 
     
     
       3. The multiple-port converter of  claim 1 , wherein the controller comprises control logic configured to send the control signals to the first and second plurality of switches to transfer energy between the first energy source and the second energy source using both phase delay control and delay time control. 
     
     
       4. The multiple-port converter of  claim 1 , wherein the controller comprises control logic configured to send the control signals to the first, second, and third plurality of switches to transfer energy from the first energy source to the second energy source using phase delay control and to transfer energy from the first energy source to the third energy source using phase shift control. 
     
     
       5. The multiple-port converter of  claim 4 , wherein the control logic of the controller is configured to vary the switching frequency of the control signals to modulate an amount of energy transferred to the secondary stage, and wherein the phase shift control modulates an amount of energy transferred to the tertiary stage. 
     
     
       6. The multiple-port converter of  claim 5 , wherein the switching frequency is the same for the primary, secondary, and tertiary stages. 
     
     
       7. The multiple-port converter of  claim 1 , wherein
 the controller has control logic configured to send first and second control signals to the first plurality of switches and to send third and fourth control signals to the second plurality of switches, 
 the third control signals are identical to the first control signal with a phase delay, and 
 the fourth control signals are identical to the second control signal with the phase delay. 
 
     
     
       8. The multiple-port converter of  claim 1 , wherein the resonant capacitor and the resonant inductor of the secondary power stage are in series with the secondary winding of the transformer. 
     
     
       9. The multiple-port converter of  claim 8 , wherein the inductor of the tertiary power stage is in series with the tertiary winding of the transformer. 
     
     
       10. The multiple-port converter of  claim 9 , wherein the primary stage has a capacitor in series with the primary winding of the transformer, the tertiary stage has a capacitor in series with the tertiary winding of the transformer. 
     
     
       11. The multiple-port converter of  claim 1 , wherein the controller comprises control logic configured to send the control signals to the first, second, and third plurality of switches to transfer energy from the second energy source to the first energy source using phase delay control and delay time control, and from the first energy source to the third energy source using phase shift control. 
     
     
       12. The multiple-port converter of  claim 1 , wherein the tertiary power stage is a first tertiary power stage among a plurality of tertiary power stages, each of the plurality of tertiary power stages connected to a respective winding of the transformer and to a respective energy source, each tertiary power stage forming a respective dual active bridge converter with the primary power stage. 
     
     
       13. A method of controlling a DC-DC converter having a plurality of stages including first, second and third stages, the method comprising acts of:
 measuring a plurality of electrical properties of the DC-DC converter; 
 determining a switching frequency, phase delay, and phase shift based at least in part on the measured plurality of electrical properties; 
 switching a first plurality of switches of the first stage at the switching frequency; 
 switching at least two of a second plurality of switches of the second stage at the switching frequency, time shifted by the phase delay relative to switching of at least one of the first plurality of switches; 
 switching at least two of a third plurality of switches of the third stage at the switching frequency, time shifted by the phase shift relative to switching of at least one of the first plurality of switches; and 
 varying the switching frequency of the first plurality of switches or the second plurality of switches to regulate current corresponding to the second power stage, 
 wherein the second power stage and the third power stage are controlled independently from each other. 
 
     
     
       14. The method of  claim 13 , further comprising acts of:
 determining a delay time based at least in part on the measured plurality of electrical properties; and 
 switching at least two other of the second plurality of switches of the second stage at the switching frequency, time shifted by the delay time relative to switching of the at least two second switches. 
 
     
     
       15. The method of  claim 13 , wherein the measuring comprises measuring at least one of a group consisting of a voltage of an energy source connected to one of the plurality of stages and a current in one of the plurality of stages. 
     
     
       16. The method of  claim 13 , further comprising an act of:
 electrically coupling the plurality of stages through a transformer having a first winding wired to the first stage, a second winding wired to the second stage, and a third winding wired to the third stage. 
 
     
     
       17. The method of  claim 16 , wherein a resonance frequency of the second stage is determined by a second stage inductor and a second stage capacitor which are in series with the second winding of the transformer. 
     
     
       18. The method of  claim 16 , wherein the third stage has a third stage inductor in series with the third winding of the transformer. 
     
     
       19. A multiple-port converter, comprising:
 a transformer having a first winding, a second winding, and a third winding; 
 a series resonant converter formed by a first power stage and a second power stage; 
 a dual active bridge converter formed by the first power stage and a third power stage, wherein the first power stage is wired to the first winding, the second power stage is wired to the second winding, and the third power stage is wired to the third winding; and 
 a controller to measure operating conditions of the multiple-port converter and to provide control signals to the first, second and third power stages, wherein the controller is configured to vary a switching frequency of switches of the first power stage or the third power stage to regulate current corresponding to the third power stage, 
 wherein the second power stage and the third power stage are controlled independently from each other. 
 
     
     
       20. The multiple-port converter of  claim 19 , wherein the controller is further configured to vary a switching frequency of control signals sent to the first and second power stage, thereby modulating an amount of energy transferred to the secondary power stage.